I'm typing this on a 2002 Mac G4 still on the original hard drive. Obviously it's not an Intel mac, like the new ones are, but I have no problems communicating with either my 2008 Intel MacBook or my hubby's 2006 Intel iMac. All three are running different OS; my old Mac can't upgrade anymore, but it doesn't matter. If I fired up my hubby's old PowerBook G3, I wouldn't have any trouble communicating with it, either. I have multiple external drives, two monitors & two printers on my old one; it all works fine. I have added 2 internal drives to it also; I do a lot of video & Photoshop.